Study of cataract epidemiology has a special significance in prevention of cataract particularly in view of its high prevalence, and the exorbitant costs involved in its management. The broad objective was to estimate the magnitude and identify risk factors for future interventions. Such studies also help in planned development of manpower and physical infrastructure, besides making an estimation for operative load. A prevalence study of cataract has recently been conducted in India at 15 different centres, each covering approximately a population of 4,000. A manual of procedures for conducting cataract prevalence studies had been prepared, tested and used for this study. These procedures were specifically adopted, keeping in view the constraints of manpower, equipment etc., and the usual community response and lack of cooperation for detailed check-ups during surveys.